Q=CV so Q is directly proportional to V but in V=W/Q Q is directly proportional to 1/V.why?

But in  the definition of V i.e., V = W/Q_o, Q_o is the unit positive test charge. So, here Q_o is not a varying quantity. Therefore, V at a point just depends on the work done in moving a unit positive test charge from infinity to that point against the electrostatic forces i.e., .